A broadcast spreader (which may also be referred to as a rotary spreader or a spin spreader) is commonly used to distribute granular materials, such as seed, fertilizers, pelletized lime, insecticides, salts, ice melts, and/or mulch to a lawn, field, pasture, paved surface, or other outdoor surface. A broadcast spreader is generally comprised of a hopper that holds the granular material. The hopper may be mounted on a frame with wheels and provided with a handle so that it can be manually pushed. More commonly, the hopper may be mounted or otherwise connected to a tractor, truck, riding mower, all-terrain vehicle (ATV), zero-turn radius mower (ZTR), or other vehicle. In this regard, the hopper may be supported on a frame with wheels and towed behind a vehicle, or it may be mounted directly to the vehicle. However, whether pushed, towed behind a vehicle, or mounted to a vehicle, the broadcast spreader distributes granular material to a lawn, field, pasture, paved surface, or other outdoor surface.
Typically, the hopper has a discharge port (or opening) in a lower portion thereof, with the granular material passing through this discharge port under the force of gravity. The material is then distributed onto a rotating fan which propels the material onto lawn, field, pasture, paved surface, or other outdoor surface. The flow of material, i.e., the amount distributed onto the rotating fan, is commonly controlled by a shutter (or gate). The gate can be selectively positioned relative to the discharge port to regulate the flow of material. In other words, the shutter (or gate) may be moved to allow a greater or lesser amount of material to pass through the discharge port. In any event, such a construction for a broadcast spreader is well-known and understood by one of ordinary skill in the art. For example, U.S. Patent Publication No. 2002/0162907, which is incorporated herein by reference, provides a detailed list of prior art references that describe the construction of a common broadcast spreader. For other examples, reference is made to U.S. Pat. No. 7,063,280 entitled “Broadcast Spreader with a Directional Control Assembly” and U.S. patent application Ser. No. 12/209,755 also entitled “Broadcast Spreader with a Directional Control Assembly,” each of which are assigned to the assignee of the present application and are also incorporated herein by reference.
However, it is recognized that most broadcast spreaders do not provide for effective control of the transfer of granular material from the hopper to the rotating fan. For instance, once the gate is opened, granular material immediately flows from the hopper and through the discharge port, regardless of whether the fan has been activated. Or, in other instances, the material “clumps up,” effectively blocking the discharge port, such that although the fan is activated, insufficient material is reaching the fan for distribution.